I'd like to see Earendil and Elwing.
I think the main setting for the start of the series will be the middle of the Second Age when Elrond is fully grown and his brother Elros is long dead. However, that doesn't rule out flashbacks to the brothers' youth.
Perhaps Maglor can make a cameo appearance.
Maglor probably perished when Beleriand was ruined, but who really knows? Especially now that both J.R.R. Tolkien and Christopher Tolkien are no longer with us.
Maglor may have died, but the Silmarillion never records his final fate apart from wandering the shores of Middle-earth and lamenting the loss of the Silmarils. Still, he was never seen among the Elves and Men in the West. It's possible he went to the east, or someone put him out of his misery.